1. Field of the Invention
The present invention relates to pressure sensitive adhesive compositions suitable for various medical applications and especially suitable for use for adhesion to the skin, in particular in the field of ostomy care. More specifically, this invention relates to adhesive compositions comprising a rubbery elastomeric base and one or more water soluble or water swellable hydrocolloids dispersed therein, the use of such adhesive compositions for the preparation of a wound dressing or an adhesive wafer for an ostomy appliance, and to wound dressings or ostomy appliances comprising such adhesive composition.
2. Description of the Related Art
Various skin adhesive agents are used today for the above mentioned purposes.
A very widespread embodiment of skin adhesive agents comprises a self-adhesive elastomeric matrix, in which water-absorbing, swelling particles, the so-called hydrocolloids, are dispersed.
Adhesive compositions comprising hydrocolloids have been known for many years. U.S. Pat. No. 3,339,549 discloses a blend of a rubbery elastomer such as polyisobutylene and one or more water soluble or water swellable hydrocolloids such as a powdery mixture of pectin, gelatine and carboxymethylcellulose. The adhesive mass has a water-insoluble film applied to one surface. A composition of this type is available commercially from E.R. Squibb and Sons Inc. under the trademark xe2x80x9cStomadhesivexe2x80x9d and is used as a skin barrier around stomas to prevent skin breakdown by the corrosive fluids discharged by the stoma.
In adhesive compositions of this type, the polyisobutylene is responsible for providing of the adhesive properties and the dispersed hydrocolloid powders absorb fluid and render the adhesive agent capable of also adhering to moist skin (wet tack). These compositions are also gaining increasing acceptance as wound dressings for dermal ulcers, burns and other exuding wounds. One major problem which has been encountered with conventional adhesive compositions comprising hydrocolloids is their susceptibility to breakdown upon exposure to body fluids. When the compositions are used as skin barriers, e.g., around stomas, absorption of fluid is desirable, but excessive swelling causes the compositions to lose their integrity by opening for leaks and the barrier must be replaced more often than is desirable from a skin protection point of view, and very often, a residue remains on the skin, which in many cases is difficulty to remove.
A number of attempts have been made to improve the properties of adhesive compositions in order to overcome the above-mentioned drawbacks.
U.S. Pat. Nos. 4,192,785 and 4,551,490 describe incorporating into an adhesive composition of a cohesive strengthening agent such as a natural or synthetic fibrous material, finely divided cellulose, cross-linked dextran, cross-linked carboxymethylcellulose or a starch-acrylonitrile graft copolymer. The cohesive strengthening agent is stated to control the rate of hydration of the composition thereby increasing the resistance against breakdown by body fluids.
U.S. Pat. No. 4,477,325 describes incorporation of a mixture of a copolymer resin of ethylene and vinyl acetate (EVA) into the adhesive composition. After mixing and moulding, the composition is subjected to ionising radiation to form a cross-linked polymer network of the EVA or comprising EVA and another cross-linked resin. The cross-linked matrix is said to provide a controlled swelling.
U.S. Pat. No. 4,496,357 describes the incorporation of fumed silica into adhesive compositions to control swelling.
EP Patent No. 0 122 344 B1 describes incorporation of one or more natural or synthetic polymers capable of developing elastomeric properties when hydrated, such as gluten and long chain polymers of methyl vinyl ether/maleic acid, into the adhesive composition. The adhesive composition is stated to be resistant to erosion by moisture and body fluids.
EP Patent No. 0 340 945 B1 describes incorporation of some polycationic hydrocolloid particles into a hydrocolloid composition. The mixture of polycationic, polyanionic and neutral hydrocolloids is stated to provide increased integrity without a concomitant decrease in absorbing capacity.
In other embodiments, styrene copolymers have been incorporated which is disclosed in a number of patent references.
In U.S. Pat. No. 4,231,369 Sorensen et al. disclose an ostomy skin barrier consisting of a styrene copolymer having dispersed therein a water soluble hydrocolloid gum and a tackifier.
In U.S. Pat. No. 4,367,732 Poulsen et al. disclose an ostomy skin barrier consisting of a water soluble hydrocolloid dispersed in a continuous phase consisting of a styrene copolymer, a hydrocarbon tackifier, and a plasticizer, an antioxidant, and an oily extender.
U.S. Pat. No. 4,551,490 (Doyle et al.) discloses medical grade pressure sensitive adhesive compositions comprising a homogeneous mixture of 5-30% of one or more polyisobutylenes, 3-20% of one or more styrene radial or block type copolymers, mineral oil, one or more water soluble hydrocolloid gums, and a tackifier. One or more water swellable cohesive strengthening agents, an antioxidant, and various other optional ingredients also may be included within the adhesive composition.
EP Patent Publication No. 81907 discloses an ostomy appliance comprising a skin barrier (A) surrounding the stoma and a coupling element (B) including an outwardly extending flange permanently affixed to the skin barrier (A) and a microporous adhesive layer (C) having an upper porous layer. The skin barrier adhesive (A) comprises a homogeneous 30-70% of a blend of low molecular weight polyisobutylene and one or more optional thermoplastic elastomers selected from medium molecular weight polyisobutylene, butyl rubber, and styrene isoprene copolymers and having dispersed therein 35-65% of one or more water soluble hydrocolloids and one or more water swellable or inert cohesive strengthening agents.
Generally speaking, these prior methods are superior to improve the integrity of adhesive compositions. Nevertheless, a need still exists for better adhesive compositions having resistance to biological fluids as well as the properties of improved adhesion to the skin and strechability.
Now it has been found that an improved adhesive composition having resistance to biological fluids as well as the properties of improved adhesion to the skin and strechability may be obtained.
The present invention relates to a pressure sensitive adhesive composition suitable for various medical applications and especially suitable for use for adhesion to the skin, in particular in the field of ostomy care. More specifically, this invention relates to adhesive compositions comprising a rubbery elastomeric base in which one or more water soluble or water swellable hydrocolloids are dispersed, ostomy appliances comprising such adhesive compositions and the use of such adhesive compositions for preparing wound dressings or ostomy appliances.
The present invention relates to a pressure sensitive adhesive composition suitable for medical purposes comprising a rubbery elastomeric base and one or more water soluble or water swellable hydrocolloids, the adhesive composition comprising a substantially homogeneous mixture of 35-50 % of one or more polybutenes, 5-20% of one or more styrene copolymers, and 20-60% of one or more hydrocolloids, wherein the mixture of one or more polybutenes and one or more styrene copolymers and one or more hydrocolloids constitutes the adhesive composition.
Without limiting the invention to any hypothesis it is believed that the combination of the styrene radial or block copolymer component and one or more polybutenes in the proportions stated above provides extensibility and both rapid and complete recovery from modular strains to the composition. The combination of the adhesive properties of the polybutenes and the absorbing properties of the hydrocolloids renders the adhesive composition of the invention especially suitable for use in ostomy appliances.
It is preferred that the styrene copolymer is a styrene-butadiene-styrene block copolymer or a styrene-isoprene-styrene block copolymer. Preferably, one or more styrene-isoprene-styrene (SIS) block type copolymers are employed.
The amount of styrene block-copolymer is preferably from 5 to 20% of the total adhesive composition.
The butene component is suitably a conjugated butadiene polymer selected from polybutadiene and polyisoprene.
The Flory molecular weight of the polybutenes to be used according to the invention is preferably from 50,000 to 60,000.
The polybutenes are preferably present in an amount of from 35-50% of the total adhesive composition.
Suitable hydrocolloids for incorporation in the adhesive compositions of the invention are selected from naturally occurring hydrocolloids, semisynthetic hydrocolloids and synthetic hydrocolloids.
More particularly, the hydrocolloids are preferably selected from guar gum, locust bean gum (LBG), pectin, alginates, gelatine, xanthan and/or gum karaya; cellulose derivatives (e.g., salts of carboxymethylcellulose such as sodium carboxymethylcellulose, methylcellulose and hydroxypropylmethylcellulose) and/or sodium starch glycolate and/or polyvinylalcohol and/or polyethylene glycol.
It is preferred to use a combination of two or more hydrocolloids. It is especially preferred to use a combination of pectin, gelatine and carboxymethylcellulose as the hydrocolloid component.
The total amount of hydrocolloids is preferably 30-50% of the total composition. An especially preferred composition according to the invention comprises 50% of a mixture of polyisibutylene and SIS and 50% of a mixture of hydrocolloids comprising gelatine, pectin and CMC.
In a preferred embodiment of the invention for use in an ostomy appliance, the adhesive component of the adhesive composition is a xe2x80x9cSwiss rollxe2x80x9d adhesive of the kind disclosed in WO 89/05619, the other, more absorbing, component, e.g. comprising a mixture of PIB and a hydrocolloid or any other suitable adhesive.
In a further aspect, the invention relates to the use of an adhesive composition comprising a rubbery elastomeric base and one or more water soluble or water swellable hydrocolloids, the adhesive composition comprising a substantially homogeneous mixture of 35-50 % of one or more polybutenes, 5-20% of one or more styrene copolymers, and 20-60% of one or more hydrocolloids, wherein the mixture of one or more polybutenes and one or more styrene copolymers and one or more hydrocolloids constitutes the adhesive composition, for securing ostomy appliances to the skin and for sealing around an ostomy, for securing wound dressings or wound drainage bandages to the skin, for securing devices for collecting urine to the skin, or for securing orthoses or prostheses to the skin.
In a still further aspect, the invention relates to an ostomy appliance for placing on the abdomen of a patient for use in collecting discharge of visceral contents comprising an adhesive composition containing a rubbery elastomeric base and one or more water soluble or water swellable hydrocolloids, the adhesive composition comprising a substantially homogeneous mixture of 35-50 % of one or more polybutenes, 5-20% of one or more styrene copolymers, and 20-60% of one or more hydrocolloids.
The ostomy appliance according to the invention may be an open or a closed appliance suitable for use in connection with a colostomy, an ileostomy or a urostomy. It may be a one-piece appliance or a body side member or face plate forming part of a two-piece appliance comprising the body side ostomy member and a separate collection bag. A separate collection bag may be attached to the body side member in any convenient manner known per se, e.g., via a coupling ring or by a flange covered with an adhesive.
An ostomy appliance according to the invention may be made from materials conventionally used for the preparation of ostomy appliances in a manner known per se in the field.
The invention is illustrated more in detail in the below Examples disclosing embodiments of the invention.
PIB: Polyisobutylene available under the trademark Vistanex from Exxon Chemical Co. as grade LM-MH.
Kraton D1107: Styrene-isoprene-styrene copolymer having a molecular weight of 212,000-260,000 (GPC) and a content of diblock 15-25%.
Getatine: Gelatine P.S.98.240.233 available from ED. Geistlich Sohne AG.
Pectin: Pectin LM 12CG Z or Pectin USP/100 from Copenhagen Pectin A/S.
CMC: Sodium carboxymethylcellulose available from Akzo under the tradename Akucell(copyright) AF2881 or from Hercules Corp. under the trademark Blanose(copyright) 9H4XF.
A Z mixer Type LKB 025 from Herman-Linden was used.